New York Times reviewer David Pogue summed up the general consensus, describing Surface as a "brilliantly conceived machine whose hardware will take your breath away - but whose software will take away your patience".

He went on to compare it to "a stunning mansion on a bluff overlooking the sea - in Somalia".

In one of the more positive assessments, Wired's Matthew Honan called the device "one of the most exciting pieces of hardware I've ever used," adding that it is "extremely well-designed; meticulous even".

Honan also praised Surface's £109.99 Type Cover add-on, which serves as a screen protector and a keyboard input, but dismissed the on-board cameras as "junk".

Built with a 10.6-inch screen, larger than the 9.7-inch display in the Apple iPad, the Windows 8 tablet is 9.3mm thick and weighs just 1.5 pounds. It has a built-in kickstand and vapour-deposited magnesium case.

Joshua Topolsky of The Verge pointed out physical defects in the tablet's design, noting that its sharp-edged kickstand poses a risk of scratching wooden surfaces. He also noted that some software performed sluggishly.

He concluded: "There may be a time in the future when all the bugs have been fixed, the third-party app support has arrived, and some very smart engineers in Redmond have ironed out the physical kinks in this type of product which prevent it from being all that it can be.

"But that time isn't right now - and unfortunately for Microsoft, the clock is ticking."

In the UK, the Surface will start from £399 for the base 32GB model, while the Touch Cover will cost £99.99 and the Type Cover £109.99. Microsoft has begun shipping the device ahead of its release on October 26.